Telegram chief executive Pavel Durov has been arrested by French police at an airport north of Paris.
Mr Durov was detained after his private jet had landed at Le Bourget Airport, French media reported.
According to officials the 39-year-old billionaire was arrested under a warrant for offences related to the popular messaging app.
The investigation is reportedly about a lack of moderators, with Mr Durov accused of failing to take steps to curb criminal uses of Telegram.
Mr Durov was born in Russia and lives in Dubai. He holds dual citizenship of the United Arab Emirates and France.
Telegram is particularly popular in Russia, Ukraine and former Soviet Union states.
The app was banned in Russia in 2018, after a previous refusal by Mr Durov to hand over user data. But the ban was reversed in 2021.
Telegram is ranked as one of the major social media platforms after Facebook, YouTube, WhatsApp, Instagram, TikTok and Wechat.
Mr Durov founded Telegram in 2013 and he left Russia in 2014…